Here is an excerpt from "The Fig: Its History, Culture and Curing" by Gustav Eisen:
"OILING THE FIGS.
In southern France—in Argenteuil and in Frette—a process is performed called ' appreter les Agues " or hastening the figs. In Argenteuil and in Frette it is employed on all the figs which are desired to ripen early, the proper time for this process being of the utmost importance. If done too early the figs will not ripen at all, but will dry and spoil.The proper time is when the fig begins to color and the skin begins to feel soft, or about seventeen days before it would regularly mature if left alone. Toward evening, if possible, a single drop of good olive oil is placed on the eye of the fig, care being taken not to spread the oil. The oil is placed on the eye by means of a wheat straw and in such a way as to touch only the center of the eye. The next day the fig shows a change and in nine or ten days it may be cut, perfectly ripe, the operation having hastened the ripening of the fig certainly from six to eight days. Such treated figs are also better, sweeter, and with smaller seeds than those which have not been oiled."
Hope it helps!